With the increase in environmental oversight, operators of power plants are pushing to discover new and better ways to remediate potential pollutants which are the byproducts of the power generation process. A variety of approaches have been developed for removal or mitigation of such byproducts resulting from coal fired power plants. One known approach is the use of dry sorbent injection (DSI) systems to reduce acid gas levels, such as such as sulfur dioxide (SO2), sulfur trioxide (SO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl). DSI involves the addition of an alkaline material (such as sodium bicarbonate, hydrated lime, or trona) into various locations of the power plant system such that the acid gases react with the alkaline sorbents to form solid salts which are removed via a particulate control device.
While DSI is a cost effective control solution, it is not without its own processing challenges. For example it is common as one step of the process to disperse solid particles of alkaline materials or other treating agent such into the gas or fluid stream in order to react with the undesired component. Those of skill in the art know dispersion lances may be used to disperse the solid particles of treating agent into the gaseous stream. Simple ejection of the particles from such nozzles, however, is not very effective in generating thorough mixing of the particles with the gas stream. Furthermore, the process can create buildup of particulate on the lance tips such that the dispersion of solids may be impacted.
It is also known to use a variety of lance assemblies permit dispersion of the particulate into the fluid stream. Existing configurations, however, have achieved only limited success in improving the dispersion of the ejected particle streams. Accordingly, a need has existed for an injection lance assembly which is fully able to produce the highly turbulent conditions required for full and effective dispersion and mixing into the gas stream of the injected particles of the treating agent.
A further limitation of the existing lance injection systems is the transient nature of the use of such injection lances. Namely, there is not necessarily a constant need for injection lances to disperse particulate into a fluid stream. Conversely, there may be a need for multiple lance systems and/or multiple injection points in the fluid stream path to maximize the efficiency of the treatment process. For instance, changes in the flow rate or other characteristics of the fluid stream may require the removal or movement of such lances. Furthermore, such changes may likewise require movement or addition of baffles or other structures to create a turbulent flow wherever such lances may be placed. However, simply adding permanently deployed baffles at multiple points in the system may result in a cumulative, deleterious impact on the pressure drop for the fluid stream being processed.
In addition, the ability to add removable structures for creating a turbulent flow at the point(s) of particulate dispersion is limited as a practical matter. Specifically, the access points that are available for inserting an injection lance are typically of a limited diameter relative to the ductwork carrying the fluid stream. However, if the baffles or similar structures are sized such that the diameter is sized to fit through the access points involved, the resulting use may provide insufficient turbulence. If the particulate cannot be better dispersed in the fluid stream to be treated, the system may require higher levels of particulate for treatment or, even worse, the system may be limited in its ability to treat the undesirable emissions within the fluid stream.
Thus, the present state of the art reflects a need for an insertable lance injection system for use in ductwork with limited access points, wherein the system enables a broad turbulent regent for improved dispersion of a solid particulate into a fluid stream for use with dry sorbent injection processes and the like.